Among various types of a small hydraulic excavators, so-called small swing type or short-radius excavator, wherein a rear end rotating radius of an upper rotating body is set to about ½ of the width of a lower traveling body, can rotate 360 degrees in such a condition that the rear end of the upper rotating body hardly projects outside the width of the lower traveling body, which is therefore suitable for work in narrow places such as urban work or subway work. In such a short-radius excavator as above, there is a severe restriction on the longitudinal length of the upper rotating body in comparison with common small hydraulic excavators in which the rear end of the upper rotating body projects outside the width of the lower traveling body when rotating, resulting in a reduction in arrangement space for devices, which makes it difficult to an employ device layouts in the common small hydraulic excavators without change. Accordingly, in the art disclosed in, for example, Japanese Patent Laid-Open Publication No. Hei. 11-269931, under the floor of an operator seat covered by a canopy are disposed a fuel tank and a battery to make effective use of the space under the floor. However, known short-radius excavators suffer from the following problems.
(1) Although it has become likely, in recent years, that cabin having a substantially sealed structure adapted to shut out outside air is provided to protect operators against outside noise, dust, etc. and that air conditioner is provided to ensure habitability of the cabin, there is no arrangement space for air conditioner in the case of short-radius excavators.
That is, in the case of large-sized machines, an air conditioner may be provided in a seat stand as shown in the art disclosed in Japanese Patent Laid-Open Publication No. 2001-295319, while in the case of short-radius excavators, there may exist part of an engine under a seat stand, resulting in a difficulty in ensuring enough space in the seat stand.
Therefore, in conventional short-radius excavators, no air conditioner is provided or the volume of a fuel tank is sacrificed to provide an air conditioner as shown in the art disclosed in Japanese Patent Laid-Open Publication No. Hei. 11-269931 above-mentioned, or an air conditioner is mounted on the ceiling of a cabin as shown in the art disclosed in Japanese Patent Laid-Open Publication No. Hei. 9-315138. However, sacrificing the volume of the fuel tank requires short fueling interval, resulting in poor operating efficiency. Also, in the case of mounting air conditioner on the ceiling of cabin, vehicle height is increased, resulting in poor carrying performance.
The present invention has been made in consideration of the above-described circumstances and a first object thereof is to provide a short-radius excavator, wherein the volume of a fuel tank is increased as much as possible with ensuring of an arrangement space for air conditioner to allow effective use of the space in a rotating frame.
(2) Also, with respect to such a short-radius excavator as above, an art for arranging an engine in a slanted manner is disclosed in, for example, Japanese Patent Laid-Open Publication No. Hei. 5-125742. In the art, a hydraulic pump is connected to one side of an output shaft in the longitudinal direction of the engine, while a cooling device is disposed at the other side. In front of the cooling device is disposed a hydraulic oil tank, and in front of the hydraulic pump and under the floor is provided a control valve.
In such a configuration as above, the hydraulic pump and the hydraulic oil tank are wide apart from each other, which results in requiring a large space on a rotating frame for the arrangement of suction pipes that cannot be bent in small radius easily due to the bore thereof having the maximum value among all pipes. Also, providing the control valve under the floor suffers from a problem in that removal work for floor plates, for example, is required to maintain the control valve, resulting in poor maintenance performance.
The present invention has been made in consideration of the above-described circumstances and a second object thereof is to provide a short-radius excavator, wherein problems that occur when arranging an engine in a slanted manner are overcome to allow effective use of the space in a rotating frame.
(3) Moreover, in the case of short-radius excavators in which working device is pivoted movably in the lateral and longitudinal directions in a protruding manner from the front end of upper rotating body, there is a little arrangement space for devices in the longitudinal direction and therefore it is difficult to employ device layouts in common small hydraulic excavators without change. In the art disclosed in Japanese Patent Laid-Open Publication No. Hei. 11-269931 above-mentioned, a control valve, etc. are disposed in the front part of a rotating frame, including the following disadvantages.
In front of the rotating frame is disposed a working device (composed of, for example, a boom, an arm, etc.), and when enlarging an upper rotating body forward to ensure an arrangement space for devices, the front rotating radius increases, resulting in a disadvantage in terms of degree of freedom in, for example, excavating work using the working device. In addition, in front of the upper rotating body is required a lot of space to arrange pipes from the control valve on the upper rotating body through hydraulic actuators such as a hydraulic cylinder of the working device.
The present invention has been made in consideration of the above-described circumstances and a third object thereof is to realize an device layout that makes effective use of the space in the width direction of a rotating frame of a short-radius excavator in which a working device is pivoted movably in the lateral and longitudinal directions in a protruding manner from the front end of the upper rotating body.